a 42 gram sample of a substance that's used to treat thyroid has a k-value of 0.1247.

N=N0e-kt

N0 = initial mass (at time t=0)
N= mass at time t
k= a positive constant that depends on the substance itself and on the units used to measure time.
t=time, in days

Question

a 42 gram sample of a substance that's used to treat thyroid has a k-value of 0.1247.

N=N0e-kt

N0 = initial mass (at time t=0)
N= mass at time t
k= a positive constant that depends on the substance itself and on the units used to measure time.
t=time, in days

boyyy · Answer

0
If you want the equation to solve for the mass of the substance at time t then, by substituting the given values into the equation:
 
N = Noe-kt
 
N = 4.2e-(0.126t) = 4.2e-0.126t
 
where the value of N is in grams. Substitute the value of time in days and solve to get the amount of the substance left.